Ovens are available which use high power radiant elements to cook. The high power radiant elements used are most commonly halogen tungsten lamps. The filaments of these lamps are low in mass and may be operated at very high temperatures (about 3000 Kelvin). These characteristics provide a means to cook food quickly with infrared radiation, while not requiring any pre-heating of the oven.
When cooking with infrared radiant energy, the rate at which food cooks depends upon the rate at which the energy that impinges on the food surface is conducted into the interior of the food. The rate in which the food cooks is also affected by the line voltage supplied to the oven. If, for instance, the line voltage is significantly below the voltage at which the oven is designed to operate (rated voltage), the lamp filament temperature will be lower and the infrared radiation available to cook decreased. A longer time will be required to cook a food item at this reduced voltage than if the same food was cooked at the oven's rated voltage. Conversely, an oven supplied with a line voltage higher than the rated voltage will cook food faster than if the line voltage is equal to the rated voltage.
The controls of an oven using high power radiant elements are greatly benefitted by the use of pre-programmed recipes, similar to those found on domestic microwave oven controls. This type of feature is especially important on an oven using high power radiant elements, as most end-users have no prior knowledge or experience cooking with an oven using halogen tungsten lamps.
These pre-programmed recipes are determined by cooking a wide variety of commonly cooked foods using particular sequences of radiant element power intensities and cooking times. These recipes are permanently stored in read-only-memory (ROM) of an electronic control microprocessor within the oven. The recipes may be recalled at any time by the end-user by pressing a particular key on a keypad on the oven.
A problem arises when the oven is used in a location where the supply voltage varies greatly from the oven's rated voltage (typically 240 VAC). Typically, a household supply for a range product of this power is 240 VAC, but can vary as much as +/-20 VAC. Moreover, in many locations, such as in department stores where the oven maybe demonstrated, or in very large metropolitan areas, the typical supply voltage is 208 VAC. The use of the pre-programmed recipes under these varying voltage conditions may result in inconsistent cooking results, i.e. underdone and overdone food.
Inconsistencies in cooking results will make the end-user frustrated and not desire to continue to learn how to use this new cooking technology. Without a solution to this consistency problem, an oven using high intensity radiant elements will find a barrier in the marketplace based on end-user complaints.
Other appliances, such as electric ranges and cook tops are also affected by this line voltage variability, but to a lesser extent. Appliances of this type are typically temperature and not time regulated, are familiar to the user, and do not include pre-programmed recipes built into the controls. These factors negate effects of line voltage variation.
The present invention is directed to a cooking method and apparatus which solves one or more of the above noted problems.